Chevrolet Repair: Scanner code, gm code, blown fuse

Question
I have a 1994 chev corisca with a 3.1 engine. The service engine light come on when idleing.OBD 1&2 scanner or the GM code scanner  will not get the codes. can you help

Answer
If your scanner is not displaying codes I would start by checking the MIL status. With the key in run, engine off does the MIL (check engine light) illuminate?

If yes, then I would jumper terminals A & B in the DLC connector together. It should flash code 12 three times and then it will flash out any trouble codes.

If this all works ok, then your scan tool may be defective.

If the MIL does not illuminate and/or flash code 12 you'll need to follow the repair manual procedure for that. Possibly blown fuse or defective ECM.